In recent years, there have been developed techniques for enhancing performance for protecting a vehicle occupant, particularly the head of the vehicle occupant, when impact force has been applied to a side section of the vehicle. For such a type of vehicle occupant protection apparatus, a technique has been developed, according to which a side curtain airbag is stored in a folded configuration or position along a side corner of a roof (roof rail) of a vehicle body so that the side curtain airbag can be deployed in a curtain shape along a vehicle window when the vehicle has been subjected to impact force greater than a predetermined intensity. Such vehicle occupant protection apparatus are disclosed, for example, in patent literature 1 and patent literature 2.
In the vehicle occupant protection apparatus disclosed in patent literature 1 and patent literature 2, the side curtain airbag has an upper communication passage for introducing gas from an inflator, and a plurality of cells (inflation portions) that inflate by gas flowing thereinto via the upper communication passage. The upper communication passage extends in a front-rear direction of the vehicle body, and the plurality of cells are arranged in the front-rear direction of the vehicle body under the upper communication passage. The cells are arranged in such a manner that their upper ends differ in height alternately. Because the upper ends of the cells are located non-uniformly in a vertical or up-down direction, the gas flows from the upper communication passage into the cells with time differences.
However, deployment of the side curtain airbag disclosed in patent literature 1 and patent literature 2, where only the upper communication passage is provided along the roof rail, cannot sufficiently protect vehicle occupants when the vehicle occupants are brought into secondary collisions against upper portions of a front pillar, center pillar and rear pillar and neighborhoods thereof.
Emergency where impact force is applied to a side portion of the vehicle is encountered in various occasions, such as a lateral collision, rollover, etc. of the vehicle. Thus, there has been a demand for the side curtain airbag to achieve an enhanced vehicle protection performance in such an emergency.
Prior Art Literature
Patent Literature 1: Japanese Patent No. 3626701
Patent Literature 1: Japanese Patent No. 3999475